Cognitive control and semantics in schizophrenia: an integrated approach.

Abstract

The authors tested whether decisions about incongruencies in the representation and processing of semantic knowledge, thought to be related to cognitive control, are selectively impaired in schizophrenia. Twenty-four patients with schizophrenia and 24 healthy comparison subjects determined the relative size of paired stimuli as they are in the real world. Stimuli were words or images. Real-world "distance" (size difference between stimuli) was manipulated within pairs, as was "congruency" between real-world and presentation size. Although patients were slower overall, both groups exhibited similar effects of "distance" and "congruency"; the task was easier when the real-world size difference between stimuli was greater and when stimuli were congruent in presentation and real-world size. Some aspects of the representation of semantic knowledge are preserved in schizophrenia, and patients use this information to control cognition in the same manner as healthy individuals.